The subject of the research is historical sources, oral Kazakh genealogies (shezhire) of the Kazakh-Nogai heroic and lyrical epic, as well as the results of Y-DNA research. The object of research is the Kazakh genus Zhagalbayly. The author examines in detail such aspects of the topic as the entry of the Zhagalbayly clan into the composition of the main peoples who stood out from the imperial super ethnos of the Golden Horde. The data on the places of settlement of Zhagalbayly in various historical periods in the post-Ordyn space are given. Various versions of such works as "Kyz Zhibek", "Kobylandy Batyr" and "Er Sayyn" in Kazakh, Nogai and Kyrgyz languages have been studied as folklore sources. The reasons and time of the emergence of the Kazakh tribal association Zhetiru, which included the genus zhagalbayly, are considered. The main conclusions of the study are to establish the availability of information about the early settlement of the ancestors of modern Kazakh Zhagalbayly clan on a vast territory from the Crimea to Afghanistan. This fact is confirmed by the presence of Zhagalbaila in the list of clans of the Crimean Khanate, Nogai Hordes, the Timurid Empire and the Kazakh Khanate. As a result of the analysis of the data of the oral Kazakh genealogy (shezhire) and the Kazakh-Nogai heroic and lyrical epic, for the purpose of their historical synthesis, the character Karabukan is established. He is represented as a batyr and a soothsayer of the Kiyat tribe troops. It is proposed to consider him as a possible legendary ancestor of the Kazakh Zhagalbayly. The results of studies of Y-chromosome polymorphism of representatives of various divisions of the Kazakh zhagalbayly are presented. When comparing the seven results of the Y-DNA12 samples, the probability that the number of generations before their common ancestor is equal to 24 generations is 91.41%. When comparing the three results for Y-DNA 67, it is equal to 99.61%. This information is consistent with shezhire, in which the distance to the common ancestor is 22-24 generations.